1.Sift flour and mustard into large bowl, rub in butter. Stir in enough milk to mix to a soft, sticky dough.
2.Turn dough onto floured surface, knead until smooth. Press dough out to about 1.5cm thickness, cut into 7cm rounds. Place rounds, just touching, onto greased oven trays; sprinkle with topping.
3.For topping, melt butter in small pan, remove from heat, stir in remaining ingredients.
4.Bake in hot oven about 15 minutes.